Scotland made desperately hard work of it in the heat of the Houston night before welcoming in Vern Cotter as their new head coach with a 24-6 win over the United States.

They scored three tries, including a penalty try, and kept their line intact, but the New Zealander who has charge of the side through to the next 2015 Rugby World Cup will now know what work he has to do if he aims to forge a team capable of challenging a team with more weapons than the USA.

The Scottish success could have been more comfortable had their handling been better. When it mattered, the Scots bossed the set-piece, but they butchered as many chances as they took and lost too many promising positions to handling mistakes.

As might have been expected with a team boasting as much experience as Scotland, they were the first to settle with Greig Laidlaw landing an early penalty after the forwards had destroyed the USA scrum.

The home side, however, were showing threats with the ball and took a lot of confidence from a rumbling 40-yard charge from Todd Clever, their captain, and almost immediately had the levelling penalty from Chris Wyles, the Saracens fullback.

There was no question, though, which team had the sharper cutting edge.

As long as the forwards were charging at each other, there was not a lot to choose between the teams, but once the likes of Stuart Hogg, the Scotland fullback, and Sean Matland, the wing, got into the action, it always caused problems for the Americans. In the end, it told, with Laidlaw spotting a gap behind a ruck and his clean solo break gave Tim Visser, the wing making his return to Test rugby after a broken leg, an easy run in for the try, his seventh in 13 internationals, that Laidlaw converted.

There should have been several more before the break. Visser spilled an easy chance carved out by Hogg and Duncan Taylor, the centre, and was later to drop the ball going for a score. Then Hogg and Visser created an opening but the pass landed short of Laidlaw, and Wyles was able to clear to touch.

In the end, it did not matter. Scotland mauled and scrummed on the home line for almost five minutes before getting Olive Kilifi, the home prop, sin-binned for dropping one scrum too many, and when the USA did the same again, Scotland eventually got their reward with a penalty try that Laidlaw converted.

Despite being a man short, the home side thought they had a try of their own when Clever powered his way to the line only to be penalised for a double movement, but they did manage to see out the rest of the first half without further damage.

What Scotland were not doing was impressing. The missed chances were merely an example of a flurry of sloppy handling on a night when the heat and sweat might have excused the occasional dropped ball but not the number of mistakes they were making. There was more of the same after the break as the heat started to take its toll on the bigger players and the match became even more stop-start. The Americans briefly cut into Scotland's lead with a second Wyles penalty.

It was always going to take a moment of brilliance to break the match open, and equally predictably it came from Hogg. His superb catch of the high ball under pressure caught the USA by surprise as they all over-ran him and gave him the space to run the score in from 50 yards. Laidlaw's equally assured touchline conversion made sure there was no way back for the home side.